This invention relates in general to resistors and, more specifically, to a novel resistor device and processes for preparing and using the device.
The resistor art is a well developed art with countless variations in compositions, properties and configurations. Although stable properties are normally sought, some resistors are sensitive to changing conditions in the ambient environment brought on by variables such as electromagnetic radiation, temperature, pressure and the like.
One ambient environment characteristic to which resistor sensitivity is normally undesirable, is humidity. Humidity sensitive resistors are useful for numerous devices such as humidity sensors, humidity control devices, or in devices where certain humidity dependent characteristics are to be controlled. Generally, humidity sensitive resistors are to be avoided for highly sophisticated, precision electrical equipment. Although humidity sensitive resistors could be utilized for humidity sensors, many humidity sensitive resistors respond very slowly to changes in humidity. Much of the change in resistivity of some humidity sensors occurs in the high resistivity region and therefore require extremely sensitive and highly sophisticated detection devices. Other humidity sensitive resistors have a limited range of incremental resistivity change with changes in humidity. For example, the humidity sensing membranes of a cured amino group containing organosilicon compound in U.S. Pat. No. 3,864,659 to Furuuchi et al exhibit a limited range of incremental resistivity change and much of the incremental change in resistivity occurs in the difficult to measure high resistivity region. Incremental changes in resistivity in the region greater than about 10.sup.10 ohm-cm are particularly difficult to accurately measure without highly sophisticated scientific research tools.
Some humidity sensitive resistors are unstable over extended periods of use under high or low humidity conditions. Still other humidity sensitive resistors may exhibit complex functional changes in resistivity with changes in humidity. Humidity sensitive resistors which have nonreversible characteristics have only limited utility. Further, other humidity sensitive resistors tend to unduly expand and contract when subjected to different levels of humidity. Such characteristics render most resistors unsuitable or marginally acceptable for use in humidity sensors or similar applications.
Thus, because of the deficiencies of many humidity sensitive resistors, there is a need for an improved humidity sensitive resistor.